Dear Ahmed,
Thanks for your reply. But it is not really what I was looking for. Sorry I didn’t explain it well.
I would like to change the ID Variation AFTER the customer paid.
See the picture below:

Direct link: https://i.goopics.net/KODy1.jpg
I would like to change the “ID Variation : 35255” to another one (so to change the attributes Body color and Door color)
But the problem is once the order is completed and paid, I cannot modify it…
Do you see what I mean?
Best regards,
Antoine.